Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious behavior: billing via x402 at $0.003 USDC per successful call, that failed calls are not charged, and that reads happen directly over RPC rather than via a paid security vendor.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single dense paragraph that front-loads the purpose and the enumerated outputs, then closes with the pricing caveat. It is longer than typical but every clause carries information (chains, proxy standards, pricing, no-charge-on-failure) with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be explained. With only two parameters, annotations covering safety, and the description covering chains, proxy standards detected, and payment terms, an agent has everything needed to decide and invoke correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the description largely restates the schema's chain list (base default, ethereum, arbitrum, optimism, polygon). It adds no format details beyond what the schema already documents, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (read on-chain facts over RPC) and resource (ERC-20 contract) and enumerates the exact data returned: name, symbol, decimals, total supply, code size, proxy status with implementation/admin, owner() and renouncement, risky bytecode functions, warning flags. This clearly distinguishes it from siblings like evm_contract, evm_address, or solana_token.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives useful context — the supported chains, that Base is the default, and that 'no paid security service is called' — which implicitly positions it against the audit sibling. However, it never states when to prefer this over evm_contract or any other sibling, and there are no explicit exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.